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[34.143.132.104]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-724de454aacsm10659057b3a.11.2024.11.27.12.56.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Nov 2024 12:56:31 -0800 (PST) Date: Wed, 27 Nov 2024 20:56:24 +0000 From: Pranjal Shrivastava To: Robin Murphy Cc: "Li,Rongqing" , "joro@8bytes.org" , "will@kernel.org" , "iommu@lists.linux.dev" Subject: Re: =?utf-8?B?562U5aSNOiBb5aSW6YOo6YKu5Lu2?= =?utf-8?B?XSBSZTogW1BBVENI?= =?utf-8?Q?=5D?= iommu: Downgrade print level for iommu group information Message-ID: References: <20241126072339.25714-1-lirongqing@baidu.com> <84cb9155-4793-45f9-bb67-6926e103dc84@arm.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Nov 27, 2024 at 12:37:38PM +0000, Robin Murphy wrote: > On 27/11/2024 10:16 am, Pranjal Shrivastava wrote: > > On Tue, Nov 26, 2024 at 12:09:03PM +0000, Li,Rongqing wrote: > > > > > > > On 26/11/2024 7:23 am, Li RongQing wrote: > > > > > This per device log is becoming longer with more and more PCI devices > > > > > in system, which slows down the boot process due to the serializing > > > > > nature of printk(). > > > > > > > > > > Downgrade dev_info() to dev_dbg() so it is still accessible for debug > > > > > purposes. > > > > > > > > Previously discussed 4 and a half years ago: > > > > > > > > https://lore.kernel.org/linux-iommu/20200302154426.GC6540@8bytes.org/ > > > > > > > > Hmm.. I'm wondering if ratelimiting might help here? > > We can define a rate_limit for the iommu subsystem that can be tuned > > accordingly to control verbosity. We can keep the rate_limit to a min. > > as we'd like and maintain it upstream and give users an option to tune > > it as per their requirement. > > No, this is not an issue of rate, and we're not going to reinvent some > obscure IOMMU-API-specific version of loglevel just for this. These are at > "info" level for good reason, so anyone who only cares about warnings or > errors can already filter their console output to suit. > Ack. Agreed. > Debug enough "my device stops working after I enable the IOMMU" issues by > email using only dmesg logs, and you might start to appreciate how often > it's a case of scrolling way way back from the apparent error to see that > the device was added to a *different* group than expected, or crucially, > seeing the conspicuous *absence* of any message, because the IOMMU driver > didn't believe it was responsible for that device in the first place. Hmm.. I agree. > > Thanks, > Robin. > Thanks, Praan